1. Field of the Invention
The present disclosure relates to an apparatus and method for controlling Dual Band Dual Modem.
2. Description of the Related Art
A DBDM (Dual Band Dual Modem) is formed with one body that includes two modems. The body is generally formed in a USB (Universal Serial Bus) dongle, and can be connected to a USB port disposed at a user terminal such as a notebook type computer.
The user terminal connected with the USB dongle type DBDM via the USB port may be wirelessly connected to a predetermined network such as Internet via one modem selected from two modems disposed at the DBDM to perform the data communication.
The two modems disposed at the USB dongle type DBDM generally includes a first modem performing EVDO (Evolution-Data Optimized) or HSDPA (High Speed Downlink Packet Access) communication, and a second modem performing WiMAX (Worldwide Interoperability for Microwave Access) communication.
The EVDO or HSDPA communication using the first modem has simultaneously an advantage and a disadvantage in that the number of nation-widely installed base stations is too many to enable performance of easy communication at any place in the nation, whereas communication charges are relatively high.
The WiMAX communication using the second modem has simultaneously an advantage and a disadvantage in that communication may be performed at a lower price over the EVDO or HSDPA communication using the first modem, whereas the number of base stations is restricted to limit places where the communication can be performed.
Therefore, terminal users determines a place as to whether the place is where EVDO or HSDPA communication using the first modem can be performed, or where WiMAX communication using the second modem can be performed, and performs data communication using one modem based on a result of the determination.
The DBDM generally includes a USB port connected to a user terminal, and a switching unit or a USB hub between the first modem performing EVDO or HSDPA communication and the second modem performing WiMAX communication, to allow the user terminal to select one of the two (first and second) modems for performance of communication.
The use of the switching unit for DBDM is to perform communication by connecting the user terminal to the first modem or the second modem through the switching unit. However, use of the switching unit has a disadvantage in that, while data communication is being performed using one modem, the other modem cannot inform the user terminal of whether a place is determined to be where data communication is possible.
For example, in a state where the switching unit is switched to the first modem to allow the user terminal to perform communication using the first modem, an operating power is supplied to the second modem to determine whether a place is where the data communication is possible.
However, the switching unit cannot inform the user terminal of whether the place is where the data communication is possible as a result of the determination, because the user terminal is connected to the first modem while the second modem is not connected to the user terminal.
Furthermore, in a state where the switching unit switches the second modem to be connected to the user terminal, the switching unit cannot inform the user terminal of whether the place is where the data communication determined by the first modem is possible.
Meanwhile, the use of USB hub is to selectively connect the first modem or the second modem to the user terminal in response to switching operation of the USB hub, and to inform the user terminal of whether the place is where the data communication respectively determined by the first modem and the second modem is possible.
However, a current supplied from the user terminal to the USB port is limited to disable to simultaneously operate the first modem and the second modem. That is, a rated current capacity capable of supplying a current from the user terminal via the USB port is limited to 500 mA.
The DBDM mounted with the USB hub an approximately 80 mA current, the first modem performing EVDO or HSDPA communication needs an approximately 450 mA current at the maximum operation, and the second modem performing WiMAX communication needs an approximately 70 mA current.
Therefore, the DBDM mounted with the USB hub may need a current capacity of approximately 600 mA for operating the USB hub, the first modem and the second modem at the same time. However, the DBDM mounted with USB hub and having a current capacity of approximately 500 mA supplied from the user terminal via the USB port cannot supply a required capacity of current from the user terminal if the first modem and the second modem are concurrently operated.
As a result, the DBDM mounted with the USB hub supplies an operating current to the first modem and the second modem by installing a separate battery, where use of separate battery is cumbersome and disadvantageous in that the size of the DBDM increases and the battery must be replaced if a charged current in the separate battery is discharged.